binaryPI: Disable CAR with empty stack

Calling disable_cache_as_ram() with valuables in stack is not a stable solution, as per documentation AMD_DISABLE_STACK should destroy stack in cache.

While we still preserve cache contents (there is wbinvd deep inside AMD_DISABLE_STACK macro), we now actually do a stack switch and much more closely meet the specification of CAR teardown sequence in AGESA specifications.

We now somewhat incorrectly include files from agesa/ tree, but the whole agesawrapper.c file removal will address the issue of overall directory layout.